In a turbojet with double flow the rotor of the fan carries a certain number of blades, each blade comprising a ribbed blade root engaged in a groove arranged on the periphery of a rim. The grooves are defined between radial projections provided with lateral bosses, covering the edges of the grooves and shaped to hold the blade roots.
During production each blade root is fitted into its groove by being made to slide through the upstream end of the latter. The upstream ends are then closed, in particular by an annular flange usually called “rear cap shroud head”. This flange is fixed on said rim of the rotor. It also enables longitudinal wedges, inserted in the grooves, to be locked under the blade roots.
In the following text the terms upstream and downstream are used respectively to indicate a position to the front or to the rear of the engine.
It is also known to close each groove at its upstream end by a bolt engaged in lateral notches machined on both sides of the groove, in said radial projections, in the vicinity of the upstream end of the groove. These notches open out in the groove and are directed so as to converge towards one another radially outwards.
The role of the bolts is important since the thrust load which the blade root exerts on each of them lies between 500 and 900 kg. Moreover, in the event of damage such as ingestion or loss of blade, the bolt allows the shock energy to be dissipated and the deterioration of adjacent parts to be minimized.